Touch control circuits



Feb. 23, 1965 c. E. ATKINS ETAL TOUCH CONTROL CIRCUITS 3 Sheets-Sheet lFiled July 5, 1960 Fig.1-

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ATTORNEYS Feb. 23, 1965 c. E. ATKINS ETAL 3,171,066

TOUCH CONTROL CIRCUITS Filed July 5, 1960 3 Sheets-Sheet 3 1/ 2 T ii 1/0H NVENTORS 61721. E. Ark/Ms ATTORNEYS cuit and restoring the circuit toinitial conditions.

United States Patent 3,171,066 TOUCH CONTROL CIRCUlTS Carl E. Atkins,West Orange, and Robert L. Ziolkowskl, South Plainfield, N.J., assignorsto Thug-Sol Electric Inc, a corporation of Delaware Filed July 5, 196a,Ser. No. 40,827 4 Claims. (Cl. 317-446) The present invention relates totouch control systems and more particularly to electrical or electroniccircuits controllable by touch of an individual. While the invention isadapted for use in control of a variety of types of circuits it isparticularly useful for control of lighting circuits, as for example forcontrol of table and floor lamps, and will therefore be described withreference to such type of control.

When a table lamp, for example, is to be lighted in a darkened room theinvention provides means whereby a relatively large area of the lamphousing or support. when touched by the hand, causes the lamp to belighted. It is desirable that once the lamp has been lighted a secondtouching of the large area will not extinguish the lamp. Accordingly,the control circuit of the invention insures against inadvertent openingof the lamp circuits by providing a locked condition of the circuit oncethe lamp has been lighted. Additional means, in the form of a smallbutton on the lamp base, or elsewhere, to be touched or pushed isprovided for opening the lamp cir- A feature of the invention is the lowstandby current required for the circuit and consequently low heatgenerated in the device and longer tube life. Another feature of theinvention is the means affording adequate protection against electricshock to the operator.

Briefly, the circuit of the invention comprises a radio frequencyoscillator which is coupled through an isolation mechanism, such as ablocking condenser or a radio frequency transformer, to the area to betouched when oscillation is to be stopped. The oscillator, when stopped,passes sufiicient current to energize a relay which over its contactscontrols the lighting circuit of the lamp. When the lamp is to beextinguished the original confition of the circuit is restored either byrestoring oscillation of the circuit by capacitative coupling throughthe operator or by momentary completion, as by a push button switch, ofpart of the oscillator circuit which has opened upon energization of therelay, or by manual tripping of an interlock coupled to the relayarmature.

For a better understanding of the invent-ion and of circuits embodyingthe same reference may be had to the accompanying drawings of which:

FIGS. 1 and 2 are side views, partly broken away, of table lampsequipped with the touch control system of the invention and illustrativeof a type of fixture that may be readily controlled;

FIG. 3 is a circuit diagram of a circuit embodying the invention andrepresenting one arrangement for touch control of both closing andopening a lamp circuit;

FIG. 4 is a diagram showing a modification of the circuit of FIG. 3 andrepresenting push button means for opening the lamp circuit;

FIG. 5 is an enlarged perspective view of the bottom of a table lampsuch as that of FIG. 2 equipped with the push button switch of thecircuit of FIG. 4.

FIG. 6 is a circuit diagram representing an embodiment of the inventionwherein the relay is provided with a mechanical interlock.

FIG. 7 is a perspective view of the bottom of a table lamp equipped withthe circuit of FIG. 6 and illustrating a suitable location of the relayfor push button release of the interlock thereof; and

3,171,066 Patented Feb. 23, 1965 ice periphery for introduction of theleads from the alternating current household supply. The annulus 8 supports an insulating disc 12 of plastic material which has mountedthereon a bracket 14. The circuit elements for control of the lightingcircuit are carried on the bracket 14. The ungrounded lead-in conductorfrom the alternating current supply is connected to one terminal of thesocket 4 and the other terminal of the socket 4 is connected to thecontrol unit, indicated generally at 16, as are also both of the lead-inconductors. Also mounted on the lamp in any readily accessible locationis a button for use in extinguishing the light. In the particularembodiment illustrated in FIG. 1 the button is shown as insulatedlymounted on the annulus 8 and identified by the reference numeral 18.This button is connected internally of the annulus and body to the unit16 and may be a touch control or a push button depending upon theparticular circuit within the unit 16. Various suitable circuits to beincorporated in the unit 16 are shown in FIGS. 3, 4, 6 and 8.

The area to be touched for causing illumination of a lamp need not be ametal surface such as the annulus 8 of FIG. 1, as it is the introductionof high frequency energy into the persons body that loads theoscillatory circuit and stops oscillation thereof and such energy can betransmitted to the body capacitatively as well as conductively.

FIG. 2 illustrates a table lamp adapted for control by the circuit ofthe invention and having a hollow ceramic body 20 the inner surface ofwhich is rendered conductive by a coating 22. of Aquadag or otherconductive material. When a lead 24 is fastened to a silver coating 26on the coating 22 and suitably connected at its other end to the controlunit (not shown in FIG. 2) within the lamp body, capacitative couplingto a person touching any part of the surface of the lamp body 20transmits high frequency energy to the person to load the oscillatorycircuit. The button 18 for extinguishing the lamp may be located on thepedestal 28 of the lamp.

One suitable circuit for the control unit 16 is shown in FIG. 3 in whichalternating supply leads from a 60 cycle volt supply are shown at 30 and32 (line 32 being the grounded lead) and the lamp bulb is represented at34 with one terminal of its socket (not shown) connected to lead 30 andwith the other terminal of the socket connected to the front contact 36of a relay 38. The relay armature is grounded so that when the relay isenergized the circuit for the lamp is closed by the armature. Anelectronic tube 40, shown as a triode, has its filamentary cathodeenergized from the alternating current lines 30 and 32 through acapacitor 42, of say one microfarad, bridged by a high resistor 43. Thecontrol grid of tube 40 is connected to the cathode and to grounded lead32 through a high grid bias resistor 44. The control grid is alsoconnected through a capacitor 46 and tank coil 48 to ground. The anodeof tube 40 is connected through a capacitor 50 and feedback coil 52 tothe back contact 54 of the relay. The anode of tube 40 is also connectedthrough a radio frequency choke 56 and the winding of relay 38 to thesupply line 30. The annulus 8 of the lamp of FIG. 1 or the body 20 ofthe lamp of FIG. 2, shown symbolically in FIG. 3 as an antenna 9, isconnected through a capacitor 58 to the oscillatory grid circuit of tube40 at a point intermediate the capacitor 46 and coil 48. The element ofthe circult of FIG. 3 corresponding to the button 18 of FIGS. 1 or 2,shown symbolically as an antenna 18a, is coupled to ground through acapacitor so and connected through a capacitor 62 to the back contact 54of the relay.

In such type circuit, when low frequency alternating voltage isimpressed across the oscillator tube, the circuit will break into highfrequency oscillation of increasing amplitude as the anode potentialincreases during the positive half cycle of the supply lines. Duringsuch oscillation electrons from the cathode accumulate in the gridcondenser at a rate too high for dissipation through the grid leakresistor. When the grid is driven sufficiently negative by theaccumulated electrons oscillation is blocked. When the negative chargedissipates through the resistor, oscillation will resume, if the anodepotential is positive. Thus, the circuit oscillates in short bursts ofhigh frequency energy, the repetition rate of the bursts depending uponthe time constant of the grid circuit and upon the frequency of theimpressed voltage. The frequency, during oscillation, may vary from twoto fifty megacycles per second, depending upon the inductance andcapacity of the tank circuit as is well known in the art. In thepreferred embodiment of the invention, the circuit is designed for oneshort burst of high frequency energy during each positive half cycle ofthe supply voltage, the duration of each burst being small as comparedto the duration of a half cycle of the supply voltage, for example ormicroseconds for each burst as compared to over 8 milliseconds for eachhalf cycle of the supply voltage. An example of suitable values for thegrid resistor 44 and for the capacitor 46 to provide but one burst ofhigh frequency energy each positive half cycle of the impressed voltagewave are 20 megohms and .005 microfarad, respectively. Preferably thetank circuit is designed for radio frequency energy of the order of 10megacycles.

While the circuit is operating as above described, the average potentialof the grid is so negative that the tube will not pass suflicientcurrent to cause actuation of the relay. These conditions are maintainedso long as the antenna 9 is not touched. The average current through thetube may be as low as 20 microamperes although the instantaneous peakcurrent during bursts of high frequency energy may reach as high a valueas 400 milliamperes. The low standby current insures long tube life, lowgeneration of heat and low power consumption. During standby conditionsas above described the circuit of the lamp is open at the front contact36 of the relay and the lamp is unlighted. If now a person touches theantenna 9 the oscillatory circuit is loaded as radio frequency energy istransmitted into the person and radiated from him. The circuit, beingincapable of supplying this additional energy, ceases to oscillate. Thenegative voltage across the grid leak resistor 44 then dissipates andthe plate current rises to a value sufficient to actuate the relay toclose the lamp circuit. This type of oscillator with its short bursts ofhigh frequency oscillation is particularly useful both because the ratioof the current through the tube when the tube is not oscillating to thatthrough the tube during oscillation is high thus insuring positiveoperation of the relay and because the amount of radiation from thistype of oscillator is a minimum and therefore there is little, if any,interference with the operation of other electronic devices. The averageidling current through the tube may be as low as 20 microamperes, asabove indicated, while the non-oscillating current may be anywhere from2 to 8 milliamperes.

When the relay is actuated it opens the ground circuit of the anodefeedback circuit and thereby prevents resumption of oscillation. Toextinguish the lamp the button or antenna 18a is touched to provide acapacitative coupling to ground sufiicient to cause the tube to resumeoscillation. Resumption of oscillation causes release of the relay,restores the ground connection for the anode feedback circuit and opensthe lamp circuit. Thus, in this embodiment of the invention resumptionof oscillation is prevented by an opening of the anode feedback circuit.

The resistor 43 bridging the capacitor 42 in the filament circuitprovides means for discharge of the capacitor when the circuit isdisconnected from the supply lines and therefore insures against a surgeof current through the filament should reconnection to the power linesbe made at a time in the voltage cycle when the phase of line 3% isopposite to that which existed when the circuit was disconnected.

Instead of providing a touch control for extinguishment of the lamp andrestoration of oscillation of the circuit, a separate ground connectionfor the anode feedback circuit could be provided under the control of apush button. This arrangement is illustrated in the diagram of FIG. 4wherein a push button 18c is shown positioned for grounding one side ofthe capacitor 62 connected to the anode feedback circuit. The otherelements of the circuit, being identical with those of FIG. 3, need nofurther description. The capacitor 62 could be omitted if desired but ispreferably provided for protection of the operator.

Alternatively oscillation could be restored by providing means formomentarily shorting the relay, as by a push button, to cause closure ofthe anode feedback circuit over back contact 54 upon release of therelay.

In FIG. 5 one suitable form of push button for restoring oscillation ofa circuit such as that of FIG. 4 is shown mounted on the pedestal 64 ofa lamp. A rod 66 having a button head 68 is slidably mounted in a sleeve70 threaded within a hole in the pedestal. The inner end of the rodengages a hook-shaped leaf spring 72 one end of which is fixed to theinner wall of the pedestal and the free end of which is normally spacedfrom a stud 74 extending through an insulating mounting plate 7 6 withinthe pedestal. A pin extending transversely of the rod 66 limits outwardmovement of the rod and the head of the sleeve limits inward movement ofthe rod. The fixed end of spring 72 is connected to a lead 82 whichextends through a hole in the plate 76 for connection to the controlcircuit (not shown in FIG. 5). could be connected above the plate 76 tothe grounded power line 32, in which case stud 74 would be connected tocapacitor 62, or directly to back contact 54 of the relay. Spring 72 isbiased out of engagement with stud 74 but makes contact therewith whenthe rod is moved inwardly by light pressure upon the button head 68. Therelatively simple and light switch above described is entirely suitablefor use in the circuit of the invention because the switch need handleno power nor need there be any appreciable potential across itscontacts.

In the embodiment of the invention shown in FIG. 6 a push buttonreleasable interlock is provided which maintains the lamp circuit closedonce the relay has picked up its armature. This arrangement permits theuse of a less sensitive relay, eliminates the necessity for bridging thewinding thereof with a condenser and consumes substantially less powerthan the circuits of FIGS. 3 and 4. As in the circuits of FIGS. 3 and 4a self-blocking oscillatory circuit is provided comprising a triode 84with its grid connected through a capacitor 86 and tank coil 88 toground, its cathode energized from the power lines 30 and 32 through thecondenser 42 bridged by resistor 43 and its anode connected to thefeedback coil 90. The bias resistor 44 is provided for the grid of tube84 and antenna 9 is coupled to the grid circuit through capacitor 58 asin the circuits of FIGS. 3 and 4. In this embodiment of the inventionthe winding of relay 92 is connected in series with the feedback coil9th between the anode of tube 84 and line 36. The lamp circuit isconnected between the front contact 94 of the relay and line Lead 82 30.The armature 96 is connected to ground and is spring biased to contactopen position. Means, indicated diagrammatically as a spring latch 98,is provided for locking the armature in contact closing position oncethe relay has been energized to pick up its armature. Push button means,indicated diagrammatically at 18d is provided for tripping the latch forrelease of the armature when the lighting circuit is to be opened.Suitable physical construction of the interlock and release thereof willbe described in connection with FIG. 7.

The operation of the circuit of FIG. 6 differs from the operation of thecircuit of either FIG. 3 or FIG. 4 in that oscillation only ceasesduring the time the tank circuit is loaded by touching antenna 9. Onlyduring such loading is the relay energized by the increased currentthrough the tube, picking up armature 6 to close the lamp circuit. Thelatch $8 then holds the armature in contact closing position,oscillation resumes with minimum average current through the relay. Whenthe light is to be extinguished the button 18a is pushed to retract thelatch 98 and permit the armature to move under its spring bias tocontact open position.

With this interlocking arrangement the power consumed by the circuitwith its normally unactuated relay is very low. Also, as the relay neednot be bridged by a condenser such as is shown at 100 in FIGS. 3 and 4,the circuit of FIG. 6 effects substantial savings as compared to thecircuits of FIGS. 3 and 4.

In FIG. 7 the relay 92 is shown mounted, as by a bracket 102 on aninsulating platform 104 such as the plate 12 of the lamp of FIG. 1 orthe plate 76 of FIG. 5. The armature 96 extends horizontally and isspring biased against a stop 1% insulatedly mounted on the relay core.Also insulatedly mounted on the core is the spring latch 98 having ahook portion 98' which, when the armature is attracted to engage contact94, rides under the end of the armature and holds it in contact closingposition. The end of the latch 98 extends downwardly through a hole 108in the platform 104. A looped spring member 1%, similar to the member 72of FIG. 5, is positioned to engage the end of latch 98 and push it in .adirection to release the armature from the hook 98 when the button 18dis pushed. The member 164) is mounted at one end on the inner wall ofthe lamp pedestal and has a stretch positioned in the line of movementof the pin portion of the push button.

A transistorized version of the circuit of the invention is shown inFIG. 8. In this embodiment of the invention the oscillatory circuitincludes a transistor 110 the emitter of which is connected through therelay 38 to ground and to the grounded alternating current supply line32 and the collector of which is connected through a tank circuit 112, arectifier 114, and a resistor 116 to one end of the secondary winding ofa transformer 118. The other end of the secondary winding is connectedto the grounded supply line 32 and the primary winding is connectedacross the power lines 39 and 32. The base of the transistor isconnected through a capacitor 120 and feedback coil 122 to the backcontact of the relay 38. The armature of the relay is grounded and thefront contact thereof is connected through the lamp 34 to the ungroundedpower line 30. The base of the transistor 11% is also connected througha resistor 124 to the anode of rectifier 114, and through a resistor 126of larger magnitude to ground. The antenna 9 is connected to the tankcircuit 112. For extinguishing the lamp a push button control, indicatedat 18c, provides an auxiliary ground connection for the feedback 122.The operation of the above described circuit is as follows. Under idlingconditions, that is when the circuit is oscillating and the lampextinguished, the current in the emitter circuit is insufiicient toenergize the relay 38. This is because of the low base current duringconditions of oscillation which reduces the current in thecollector-emitter circuit to a value insufiicient for energization ofthe relay. When, however, the collector tank circuit is loaded bytouching the antenna 9 oscillation ceases, the current through thecollector-emitter circuit increases sufliciently to energize the relayto open the ground connection of feedback coil 118 and complete thecircuit of lamp 34. The lamp 34 thereupon lights and a stablenon-oscillating condition is established. When the lamp is to beextinguished the push button 18s is manipulated to momentarily provide aground connection for the feedback coil 118. Accordingly oscillation isresumed, the relay releases and closes the ground connection for thefeedback circuit.

The invention has now been described in connection with variousembodiments thereof. It will be apparent from the foregoing descriptionthat the circuits of the invention could be employed for other thancontrol of the specific type of table lamp shown in FIGS. 1 and 2. Theantenna 9 may be considered as any relatively broad area available fortouching in a darkened room, as, for example, a wall panel for lightingoverhead lamps and the button 18 can be considered as any device, whichonce there is light, can be readily located for touching or pushing as,for example, an insulated button set into the wall panel. The circuitsof the invention, as heretofore indicated, consume relatively smallstandby wattage. The provision in the circuits of FIGS. 3, 4 and 6 ofthe reactive impedance comprising capacitor 42 permits the cathode ofthe electronic tube to be energized directly from the alternatingcurrent lines and to consume therefrom but a small wattage of the orderof one-half watt.

A further advantage obtained by the use of the capacitor in theenergizing circuit for the filamentary cathode is that the phase of thecurrent in the filament is in quadrature with that of the voltage on theplate. Accordingly during the half cycles when the tube conducts therewill be substantially no voltage drop across the filament and maximumcurrent will be available for energization of the relay.

The provision of a self-blocking oscillator in the above describedcircuits, serves, as heretofore indicated, to yield large change incurrent through the relay and thus insure positive action thereof.Relatively few parts are required and these, as indicated qualitativelyin FIG. 1, can be incorporated in a relatively small space. Otheradvantages of the invention will be apparent to those skilled in theart.

The following is claimed:

1. A system for controlling energization of a circuit in response totouch of an individual comprising in combination a normally oscillatingcircuit including an electronic valve, a source of energy, a relayhaving a winding connected in series with said valve across said source,said valve when the circuit is oscillating, passing insufiicient currentfor actuation of said relay and when oscillation of the circuit issuppressed passing sufiicient current for actuating said relay, anormally open circuit to be controlled, means responsive to actuation ofsaid relay for closing said normally open circuit, means for loadingsaid oscillatory circuit to suppress oscillation thereof, said lastmentioned means comprising an element coupled to said valve and whichwhen touched by an individual draws energy from the oscillatory circuit,means responsive to actuation of said relay for maintaining closed saidcontrolled circuit irrespective of subsequent touching of said elementand separate operator controlled means for releasing said relay, saidvalve being an electronic tube having an anode, a grid and a controlelectrode and said normally oscillatory circuit including coupledfeedback anode and tank grid circuits, said element being coupled tosaid grid tank circuit and said relay when actuated opening said anodefeedback circuit and said operator controlled means comprising means forcompleting the anode feedback circuit for resumption of oscillation withconsequent release of the relay.

2. The system according to claim 1 wherein said last mentioned meanscomprises a second element coupled to the anode feedback circuit andcapacitatively closing such circuit when touched by an individual.

3. The system according to claim 1 wherein said last mentioned meanscomprises a push button switch in the anode feedback circuit.

4. A system for controlling energization of a circuit in response totouch of an individual comprising in combination a normally oscillatingcircuit including an electronic valve, a source of energy, a relayhaving a winding connected in series with said valve across said source,said valve when the circuit is oscillating, passing insulficient currentfor actuation of said relay and when oscillation of the circuit issuppressed passing sutlicient current for actuating said relay, anormally open circuit to be controlled, means responsive to actuation ofsaid relay for closing said normally open circuit, means for loadingsaid oscillatory circuit to suppress oscillation thereof, said lastmentioned means comprising an element coupled to said valve and whichwhen touched by an individual draws energy from the oscillatory circuit,means responsive to actuation of said relay for maintaining closed saidcontrolled circuit irrespective of subsequent touching of said elementand separate operator controlled means for releasing said Referencestitted in the file of this patent UNITED STATES PATENTS 2,390,221Lindsay et al. Dec. 4, 1945 2,505,577 Rich Apr. 25, 1950 2,584,728Michel Feb. 5, 1952 2,695,402 Gray Nov. 23, 1954 2,732,545 Passow et a1Jan. 24, 1956 2,810,066 Green Oct. 15, 1957 2,896,131 Schumann July 21,1959 3,019,313 Stites Jan. 30, 1962 FOREIGN PATENTS 871,615 GreatBritain Sept. 5, 1956

1. A SYSTEM FOR CONTROLLING ENERGIZATION OF A CIRCUIT IN RESPONSE TOTOUCH OF AN INDIVIDUAL COMPRISING IN COMBINATION A NORMALLY OSCILLATINGCIRCUIT INCLUDING AN ELECTRON VALVE, A SOURCE OF ENERGY, A RELAY HAVINGA WINDING CONNECTED IN SERIES WITH SAID VALVE ACROSS SAID SOURCE, SAIDVALVE WHEN THE CIRCUIT IS OSCILLATING, PASSING INSUFFICIENT CURRENT FORACTUATION OF SAID RELAY AND WHEN OSCILLATION OF THE CIRCUIT ISSUPPRESSED PASSING SUFFICIENT CURRENT FOR ACTUATING SAID RELAY, ANORMALLY OPEN CIRCUIT TO BE CONTROLLED, MEANS RESPONSIVE TO ACTUATION OFSAID RELAY FOR CLOSING SAID NORMALLY OPEN CIRCUIT, MEANS FOR LOADINGSAID OSCILLATORY CIRCUIT TO SUPPRESS OSCILLATION THEREOF, SAID LASTMENTIONED MEANS COMPRISING AN ELEMENT COUPLED TO SAID VALVE AND WHICHWHEN TOUCHED BY AN INDIVIDUAL DRAWS ENERGY FROM THE OSCILLATORY CIRCUIT,MEANS RESPONSIVE TO ACTUATION OF SAID RELAY FOR MAINTAINING CLOSED ANDCONTROLLED CIRCUIT IRRESPECTIVE OF SUBSEQUENT TOUCHING OF SAID ELEMENTAND SEPARATE OPERATOR CONTROLLED MEANS FOR RELEASING SAID RELAY, SAIDVALVE BEING AN ELECTRONIC TUBE HAVING AN ANODE, A GRID AND A CONTROLELECTRODE AND SAID NORMALLY OSCILLATORY CIRCUIT INCLUDING COUPLEDFEEDBACK ANODE AND TANK GRID CIRCUITS, SAID ELEMENT BEING COUPLED TOSAID GRID TANK CIRCUIT AND SAID RELAY WHEN ACTUATED OPENING SAID ANODEFEEDBACK CIRCUIT AND SAID OPERATOR CONTROLLED MEANS COMPRISING MEANS FORCOMPLETING THE ANODE FEEDBACK CIRCUIT FOR RESUMPTION OF OSCILLATION WITHCONSEQUENT RELEASE OF THE RELAY.